1. Field of the Invention
The present invention relates generally to an inspection system that uses a scanning electron microscope, and more particularly, to an inspection system that uses a scanning electron microscope to perform inspections of an object under atmospheric conditions without limitation of the size of the object.
2. Description of the Related Art
In general, flat panel display devices such as liquid crystal display (LCD) devices and organic light emitting diode (OLED) display devices are formed by depositing a plurality of thin films and wires on a substrate. In order to inspect for the existence of imperfections such as impurities or particles on a thin film of a flat panel display device or for short circuits between the wires, an inspection system constructed with a scanning electron microscope (SEM) is used.
A vacuum scanning electron microscope may be used in the inspection system. The size of a specimen to be observed by a contemporary SEM is limited by the size of a vacuum chamber of the SEM. A vacuum scanning electron microscope that is capable of observing a semiconductor wafer fabricated up to 30 inches in width has been developed; however, usage of the such a vacuum scanning electron microscope is difficult for purposes such as conducting an inspection of the flat panel display devices of the size from 730 mm×920 mm to 2200 mm×2500 mm due to the size limitations on the vacuum chamber of the SEM.
When the size of the vacuum chamber is increased so as to be able to receive a flat panel display device, by a workpiece such as a secondary electron (SE) or a back-scattering electron (B SE) generated an object to be inspected that is to be inspected and that has been positioned in the vacuum chamber is deleteriously affected by interference caused by a charging effect generated in the vacuum chamber so that observation of an image of the object to be inspected becomes difficult, and carbon contamination by a hydrocarbon compound (HxCx) may be generated by a pump used for the vacuum chamber.
The foregoing discussion of this information disclosed in this Background section is only for enhancement of an understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.